Calculus help?

Discussion in 'Homework Help' started by Bigcountry, Dec 6, 2008.

  1. Bigcountry

    Thread Starter Active Member

    Jul 4, 2008
    71
    0
    I am having a hard time putting the differentiation equation together maybe someone could point me the in right direction. here is the problem :


    A particular factory manufactures n units per month. Each unit sells for c dollars. The number of units sold varies with the selling price according to

    n=600-10c

    and the monthly operating cost of the factory is given by
    C=4000+12n

    The monthly profit
    P=nc-C

    is the maximum when the unit selling price is
    (1) $42
    (2) $36
    (3) $420
    (4) $90

    I am just having a hard time getting the equation for it. I guess I am stuck deep just need a kick start.

    thanks for any help anyone could give me some advice.
     
    Last edited: Dec 6, 2008
  2. blazedaces

    Active Member

    Jul 24, 2008
    130
    0
    Well, maybe the following will help you:

    You want the maximum dependent variable profit P in terms of the independent variable unit price c.

    Let me ask you. If you wanted to find the local max/min of a function y(x) how would you go about doing that?

    Hope this helped. Good luck,

    -blazed
     
  3. hitmen

    Active Member

    Sep 21, 2008
    159
    0
    Play arond with eqn until you can express P in terms of c only. You shld get a quadratic equation.

    Thereafter find DP/Dc when it is 0. you shld get the answer.
     
  4. Bigcountry

    Thread Starter Active Member

    Jul 4, 2008
    71
    0
    thanks for your (the two of you) help. I was heading in the right direction. Just wasn't sure. it is hard to do problems with a flashlight in the dark. I know I made a couple of small mistakes.
     
  5. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    The correct answer is $36 if that helps.
     
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